The present invention relates to a field-sequential type display device for performing color display by synchronizing the light emission timing of each emission color with the input of pixel data corresponding to each emission color.
Along with the recent development of so-called information-oriented society, electronic apparatuses, such as personal computers and PDA (Personal Digital Assistants), have been widely used. Further, with the spread of such electronic apparatuses, portable apparatuses that can be used in offices as well as outdoors have been used, and there are demands for small-size and light-weight of these apparatuses. Liquid crystal display devices have been widely used as one of the means to satisfy such demands. Liquid crystal display devices not only achieve small-size and light-weight, but also include an indispensable technique in an attempt to achieve low power consumption in portable electronic apparatuses that are driven by batteries.
The liquid crystal display devices are mainly classified into a reflection type and a transmission type. In the reflection type, light rays incident from the front face of a liquid crystal panel are reflected by the rear face of the liquid crystal panel, and an image is visualized by the reflected light; whereas, in the transmission type, an image is visualized by the transmitted light from a light source (back-light) placed on the rear face of the liquid crystal panel. Since the reflection type liquid crystal display devices have poor visibility because the amount of the reflected light varies depending on environmental conditions, transmission type liquid crystal display devices are generally used as display devices of, particularly, personal computers that display multi-color or full-color images.
Regarding color liquid crystal display devices, at present, a TN (Twisted Nematic) type using a switching element such as a TFT (Thin Film Transistor) is widely used. Although this TFT-driven TN type liquid crystal display device has high display quality compared to an STN (Super Twisted Nematic) type, it requires a back-light with high intensity because the light transmittance of the liquid crystal panel is only 4% or so at present. Therefore, a lot of power is consumed by the back-light. Moreover, since color display is realized using color filters, a single pixel needs to be composed of three sub-pixels, and thus a high-resolution display is difficult to achieve and the purity of the display colors is not sufficient.
In order to solve such problems, the present inventor et al. developed a field-sequential type liquid crystal display device that displays a color image by using, as a liquid crystal element, a ferroelectric liquid crystal element or an anti-ferroelectric liquid crystal element which responds at high speed to an applied electric field and by causing a single pixel to emit lights of three primary colors in a time-divided manner.
Such a liquid crystal display device realizes color display by combining a liquid crystal panel using a ferroelectric liquid crystal or anti-ferroelectric liquid crystal having a high response speed of several hundreds to several μs order with a back-light capable of emitting red, green and blue lights in a time-divided manner, and synchronizing the switching of a liquid crystal element with a light emission of the back-light.
Since a field-sequential type display device as described above does not require sub-pixels, it is possible to easily realize more resolvable display compared to a color-filter type liquid crystal display device. Moreover, since this display device can use the light emission of a light source as it is for display without using color filters, it has the advantages of high brightness, excellent display color purity, high light utilization efficiency, low power consumption, etc.
However, it is difficult to use a field-sequential type display device as a reflective type/transreflective type display device like a color-filter type display device. When a field-sequential type display device is used in a portable apparatus designed for indoor and outdoor use, there is a visibility problem in outdoor use.